What is the Difference Between XHTML and HTML?

Many webmasters still create web pages in various standards of HTML. There is no pressing need to switch to newer standards because support for these will not cease to exist in the near future. While there is still wide browser support for older standards, there are benefits to switching to newer standards like XHTML. So what is XHTML anyway?

XHTML 1.0 was released over 11 years ago, making it pretty “old” by today’s fast-paced standards. It stands for Extensible Hypertext Markup Language, which extends the version of the widely used HTML that was taught to us back in the infancy of the World Wide Web. It is an application of a more restrictive markup language called XML, and because of this, XHTML documents need to be well-formed unlike HTML which requires more lenient parsing.

What is the difference between XHTML and XML? There is only one glaring difference: XHTML must be well-formed XHML while HTML does not need to be. This is where most lazy webmasters draw their complaints from. I mean why should they fix something that isn’t broken? What is the benefit of XHTML over HTML?

XHTML future-proofs all the websites you create in XHTML. Its notation, though strict, is well-formed and has improved interoperability with existing and future markup languages. XHTML allows HTML to be more extensive by being interoperable with other XML subsets like MathML, SMIL, or SVG. There is no way you can do that with plain old HTML.

Additionally, once you learn to write your code in XHTML, it becomes second nature for you to write your code properly instead of being lazy. For example, tags that do not have opening and closing tags must be explicitly closed as follows:

HTML way: <br>
XHTML way: <br />

Browsers have long spoiled lazy web designers. Paragraph tags (<p>) can be left unclosed and they would still display properly in most browsers. There was also a “flexibility” of whether or not to use quotes within attributes like:

<option selected=”yes”>
<option selected=’yes’>
<option selected=yes>

Some required elements are not treated as such in traditional HTML like the HEAD or BODY tags, and the browser spoils the designer by automatically adding these for them when it parses the code. XHTML forbids these practices.

Once you learn to write your code properly, you are not only future-proofing the website, you are also future-proofing your skills.